Gold has been used in the treatment of progressive rheumatoid arthritis since the 1920's although its mode of action is not known. Despite their documented usefulness, the dosing regimen for gold salts is largely empirical. The present study is aimed at elucidating the pharmacokinetics of gold sodium thiomalate in arthritics in an attempt to develop individualized dosing regimens that minimize toxicity and maximize therapeutic benefit. To accomplish this, the time course of the therapeutic and toxic responses to gold must be related to the time course of the drug levels in accessible biological fluids such as, plasma, saliva or red blood cells. The correlation of saliva and/or whole blood gold levels with clinical response or toxicity, a relationship not consistently found for plasma gold levels, should diminish the number of patients with gold toxicities by dosage adjustments that will not allow gold to reach a level associated with toxicity. By decreasing the toxicities through prophylactic monitoring of gold levels, the drop-out rate for chrysotherapy, at present very significant, may decrease. Identifying a therapeutic range of gold levels followed by monitoring these levels and adjusting doses to maintain the patient's gold level within this range may increase the number who favorably respond to this drug. Projected studies include administering a single dose of gold in arthritic volunteers and following the gold levels as a function of time to define the disposition kinetics of the drug. Other studies are designed to monitor gold levels in patients on chronic gold therapy and correlating these levels to laboratory and physical findings related to therapeutic benefit and toxicity. Results of these studies should allow for individual dosing of gold sodium thiomalate based pharmacokinetic parameters and determination of a therapeutic range, thereby giving the practitioner a valuable tool for management of patients on gold therapy.